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开式循环水系统运行方式的优化节能技术 总被引:2,自引:0,他引:2
1设备概况华能威海电厂二期2×300MW机组开式循环水系统由电动旋转滤网、开式循环泵、笼式滤网、主机冷油器和板式换热器等装置组成,系统如图1所示。开式循环泵由上海水泵厂提供,为24shv-19型,正常运行时一台运行,一台备用。当夏季水温高于30℃时,两台开式循环泵可同时投入运行。系统按夏季板式换热器闭式水进水温度为42℃,出水温度为37·5℃,闭式水流量为1475·5t/h,海水进水温度30℃,出水温度34℃设计的;正常运行时,闭式水出水温度<35℃。主机冷油器出口油温38~42℃,达49℃时光字牌报警。图1开式循环水系统示意图2运行方式优化的起因二期… 相似文献
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为了节约天然气脱硫中MDEA再生过程能源的消耗,利用热泵节能的原理设计并制作了一台制冷功率为23 kW、蒸发温度为5℃、冷凝温度为85℃和系统最大压力为2 MPa的热泵实验装置,通过调节水系统和热泵系统工况使之与MDEA溶液的再生过程相似。并根据实验数据绘制了水系统温度、流量与热泵系统COP和PBP之间的关系,从理论上确定了系统运行最经济参数。最后将确定的系统运行最经济参数进行验证分析,得出在此参数范围内热泵经济运行的可行性。 相似文献
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在太阳能热发电站中,抛物面槽式集热系统多回路的流量分配特性对集热工质出口温度和电站运行性能具有重要影响。传统U型集热回路采用调节阀可实现各回路流量的平衡分配,但对系统的控制水平要求较高,且建设成本较大。该文以熔盐槽式集热系统为研究对象,提出采用Z型布置结合母管变径的新型集热回路,以实现多回路流量自平衡;通过开展流量分配的理论设计计算,以及基于Apros软件搭建的集热系统动态仿真模型,研究太阳直接法向辐射DNI、入口质量流量变化以及云遮扰动工况下,Z型集热回路的流量分配、出口温度和回路压降的稳态和动态变化规律。研究结果表明,槽式集热回路Z型布置结合母管变径的方式在稳态和瞬态工况下都具有较好的流量自平衡特性。 相似文献
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本研究建立了超临界机组及其控制系统的数学模型,编制了机组变工况特性计算软件,研究了一次调频对超临界机组汽轮机动态热力特性影响的规律。采用集总参数和分布参数相结合的方法建立了机组的动态数学模型,对不同运行工况下机组的静态和动态特性进行了分析,得到了机组不同运行工况下负荷扰动及调节系统参数对机组流量、调节级后压力和温度、再热器后温度影响的规律。结果表明,随着负荷扰动的增大,无论机组定压运行还是滑压运行,各物理量动态过程中的百分比超调量不变,机组高、中压各级温度的变化可以忽略。机组滑压运行时,在维持锅炉出口温度不变的条件下,随着流量压力环节时间常数和功率流量环节时间常数的增加,高压调节级后的温度变化约1.5℃,再热器后温度变化约0.2℃。因此,一次调频对超临界机组不同运行工况下热力参数动态特性的影响非常小,不会影响机组运行的安全性和稳定性。 相似文献
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为了研究液态金属冷却快堆的运行模式和控制方案,需要对直流蒸汽发生器进行合理的建模仿真,以研究其动态特性。针对某大型钠冷快堆的直流式蒸汽发生器,采用Matlab/Simulink平台,基于三大守恒方程,建立了一种工艺仿真模型,包括稳态计算方法和瞬态计算模型。仿真结果表明,该模型的稳态精度较高,与设计参数的稳态误差在1%以内,且计算速度较快,能够满足控制系统设计的需求。基于该模型,对蒸汽发生器出口蒸汽参数的动态响应特性进行了仿真研究,得到了出口蒸汽和温度随入口钠、水参数阶跃变化的特性曲线,发现在其他条件不变时,直流蒸汽发生器出口蒸汽温度主要受入口钠温度影响,而出口蒸汽压力的主要影响因素为给水流量。在设计控制系统时,应当将钠入口温度作为蒸汽温度的主要调节参数,而将给水流量作为蒸汽压力的主要调节参数。 相似文献
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Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden. 相似文献
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《热能动力工程》2014,(5)
正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%. 相似文献
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The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°, −5°, +5°, +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods. 相似文献
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A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified. 相似文献
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As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied. 相似文献
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The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σred = σ1 β + (1 − β)σi, where: σ1-maximal principal stress, σi-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures. 相似文献
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Jaime Massanet-Nicolau Alan Guwy Richard Dinsdale Giuliano Premier Sandra Esteves 《International Journal of Hydrogen Energy》2010
Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H2 kg−1 VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min−1 successfully prevented a decline in hydrogen production and resulted in a yield of 27.0 L H2 kg−1 VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production. 相似文献